The field of the invention relates generally to electrochemical energy storage devices and methods of manufacture, and more specifically to electric double layer capacitor (EDLC) devices and methods of manufacturing such devices.
In electrical systems, secondary sources of current make it possible to accumulate, store and release electrical power to an external electric circuit. Among these secondary sources are conventional batteries, conventional capacitors and electrochemical capacitors.
One type of electrochemical capacitor is an electric double layer capacitor (EDLC) device that may sometimes be referred to as a supercapacitor. Supercapacitors typically have specific capacitance of greater than 100 F/g, as opposed to conventional capacitors with specific capacitance on the order of only several F/g. Supercapacitors are used in a variety of different applications, including but not limited to memory backup to bridge short power interruptions, battery management applications to improve the current handling of a battery or to provide a current boost on high load demands, fuel cell applications to enhance peak-load performance, regenerative braking on vehicles, and vehicle starting systems.
An electrochemical supercapacitor conventionally includes a sealed housing filled with an electrolyte, a positive electrode (cathode) and a negative electrode (anode) placed inside the housing, a separator such as a membrane that separates the anode space from the cathode space, and special lead terminals coupling the supercapacitor to external electric circuits. Manufacturing difficulties and voltage limitations exist in known supercapacitor constructions, and improvements are desired.